Left ventricular wave speed

Left ventricular (LV) wave speed (LVWS) was studied experimentally and conf irmed in theory. Combining the definition of elastance (E) with the equatio ns for the conservation of mass and momentum shows that LVWS is proportiona l to the square root of ELA, where L is long-axis length and A is the cross -sectional area, and the density of the blood. (We defined ELA = gamma, whe re gamma is compressibility.) We studied nine open chest, anesthetized dogs , three of which were studied during caval constriction when LV end-diastol ic pressure was less than or equal to0 mmHg. The hearts were paced at simil ar to 90 beats/ min, and LV cross-sectional area was measured by using two pairs of ultrasonic crystals; E was calculated from the LV pressure-area lo op. A pulse generator was connected to the LV apex, and LVWS was measured b y using two pressure transducers: one near the apex and the other near the base. Their distance was measured roentgenographically and compared with th e diameter of a reference ball. LVWS ranged from similar to1 m/s during dia stole to similar to 10 m/s during systole. The slope of the log c (where c is wave speed) vs. log gamma was 0.546, which is in agreement with theory ( 0.5). When gamma less than or equal to 0, LVWS was similar to1.5 m/s.